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  1. #1
    craigclu's Avatar
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    pH Effect on Film Development

    I'm having a hard time getting a true grasp on the effects of pH in film developers. It seems that with traditional (non-staining) developers, moving, for instance from 8.00 to 8.20 has a rather distinct effect on developer activity. When working with catechol concoctions recently, it seems that one needs to be at 10.5 to 11.0 ranges to achieve reasonable activity. Could someone who is versed in this help put some sense to this for me? I assume it must be related to surface development/staining issues but I'm just guessing at best.

    Somewhat related: Has anyone done any work on staining monobath concentrates (TEA/PG based) that can create required alkaline levels without relying on a second component for this duty?
    Craig Schroeder

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    Every developing agent needs a particular pH range in order to function.

    Metol, for example, works in a low pH environment, Rodinal (paraminophenol hydrochloride), high. At low pH, Rodinal doesn't work. At high pH, metol fogs. That's it. There really isn't any magic to pH.

    Of course every good developer has it's own character; all are magic.

    As we learn from Harry Potter, the trick is in learning how to make the magic work.

    Don

    "The purpose of Art is to transform the Artist."

  3. #3
    gainer's Avatar
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    Different agents require different pH levels for different levels of activity. If that is not simple for you, join the crowd. You can add different combinations of developing agents to the mystery.

    It is really a matter of experimentation. Reading a lot of technical journals and books helps. Some think that it all should be predictable, and it may be when the proper axioms are available.

    A very simple staining developer that works quite well is as follows:

    9 or 10 grams pyrogallol
    100 ml TEA

    Heat till it dissolves. Shouldn't take more than about 160 F. It will stay in solution when it cools.

    Dilute with water just before use. 1 part concentrate to 25 or more parts of water. You'll have to play with developing times. At 1+25 it should act about like D-76 where time is concerned.

    The only problem with this formula is that TEA freezes at about 70 F. The stock has a very long life and need not be refrigerated. I keep mine in a brisker oven (used by bread makers for rising dough) at about 104 F. You could also thin out the stock with some propylene glycol and just use more in the working solution. While you're at it, you can add a tiny bit of amidol or phenidone just to see what happens.
    Gadget Gainer

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    Quote Originally Posted by craigclu
    I'm having a hard time getting a true grasp on the effects of pH in film developers. It seems that with traditional (non-staining) developers, moving, for instance from 8.00 to 8.20 has a rather distinct effect on developer activity. When working with catechol concoctions recently, it seems that one needs to be at 10.5 to 11.0 ranges to achieve reasonable activity. Could someone who is versed in this help put some sense to this for me? I assume it must be related to surface development/staining issues but I'm just guessing at best.

    Somewhat related: Has anyone done any work on staining monobath concentrates (TEA/PG based) that can create required alkaline levels without relying on a second component for this duty?
    Craig, in answer to the first part of your question, Sandy King has done a lot of experimentation with staining catechol developers and the most effective pH level for them. Much of this information is published on Unblinking Eye and additional information can be found by searching APUG and the Azo Forum.

    For the second part of your question, Monobath implies the incorporation of a fixing agent into the recipe. I have not yet compounded (or attempted to compound) a staining monobath.

    I have used triethanolamine (TEA) as the solvent in several concentrated developer stock solutions. With the addition of water, the TEA becomes the alkali (with pH in the 9.5 - 10 range).
    Tom Hoskinson
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  5. #5

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    Quote Originally Posted by craigclu
    I'm having a hard time getting a true grasp on the effects of pH in film developers. It seems that with traditional (non-staining) developers, moving, for instance from 8.00 to 8.20 has a rather distinct effect on developer activity. When working with catechol concoctions recently, it seems that one needs to be at 10.5 to 11.0 ranges to achieve reasonable activity. Could someone who is versed in this help put some sense to this for me? I assume it must be related to surface development/staining issues but I'm just guessing at best.

    Somewhat related: Has anyone done any work on staining monobath concentrates (TEA/PG based) that can create required alkaline levels without relying on a second component for this duty?
    As others have indicated, all reducers have a pH threshhold level of activity and a higher level of pH for full activity. This varies quite a bit, from a very low threshold for amidol to a very high one for hydroquinone and pyrocatechin. When you throw another reducer into the mix and get synergism between the two the absolute figure for any single reducer may change.

    My experience with TEA, at least the version that I have purchased, is that the working pH is almost ideal for pyrogallol, about pH 9.2, but a bit too low for full energy with pyrocatechin and hydroquinone, which have a threshold of activity over pH 10. That is not to say that these reducers will not work if mixed in TEA, only that they will have more energy when the activator has a higher pH, as is the case with the carbonates, TSP and hydroxides. ON the other hand, adding one or two other reducers, such as phenidoine and ascorbic acid, throws all of this into a land where only experimentation can answer the question.

    Sandy
    Last edited by sanking; 07-25-2005 at 10:21 AM. Click to view previous post history.

  6. #6
    craigclu's Avatar
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    I carelessly used the term "monobath", thinking of a single mix concentrate and not self-fixing. I was curious as to possible reducers (I guess that's the term to use) that could be incorporated into the single solution concentrate. Are the potassium family likely to be more soluble in TEA/PG as they are in water? I've got some things doing most of what I want them to with a blend of TEA and PG but require a pH boost with sodium carbonate or sodium hydroxide secondary additions and had a curiosity about what possibly could be used in a single solution concentrate. I like how my catechol, ascorbic acid, Dimezone-S (or phenidone, too) and BZT go into suspension at lower temps in the PG. I then top off with TEA and get blends that don't give viscosity/freezing battles in my cold basement darkroom.

    I'm feeling re-energized about photography in the last couple of years by getting more involved in tuning developers/curves to my tastes and needs. I feel like I'm 95% of the way to what I want at this point so I'm at the point where it gets harder! I might be wishing for too much to incorporate this all into a single solution developer.
    Craig Schroeder

  7. #7

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    Re the second part of the question,I recently made up a basic formula attributed to Patrick Gainer which I call PCQ-TEA staining developer.The formula is 10g Hydroquinone,1g Ascorbic acid, 0.2g Phenidone, TEA to 100ml. I hope to report results in due course.

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    Quote Originally Posted by craigclu
    I carelessly used the term "monobath", thinking of a single mix concentrate and not self-fixing. I was curious as to possible reducers (I guess that's the term to use) that could be incorporated into the single solution concentrate. Are the potassium family likely to be more soluble in TEA/PG as they are in water? I've got some things doing most of what I want them to with a blend of TEA and PG but require a pH boost with sodium carbonate or sodium hydroxide secondary additions and had a curiosity about what possibly could be used in a single solution concentrate. I like how my catechol, ascorbic acid, Dimezone-S (or phenidone, too) and BZT go into suspension at lower temps in the PG. I then top off with TEA and get blends that don't give viscosity/freezing battles in my cold basement darkroom.

    I'm feeling re-energized about photography in the last couple of years by getting more involved in tuning developers/curves to my tastes and needs. I feel like I'm 95% of the way to what I want at this point so I'm at the point where it gets harder! I might be wishing for too much to incorporate this all into a single solution developer.

    Pat Gainer has stated that there is a commercial version of TEA that has a higher pH than the stuff we get from the Chemistry Store. That might be worth looking into if your goal is to make a very energetic one solution developer with pyrocatechin.

    Sandy

  9. #9
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    Sandy, I recall that you used sodium bisulfite in your Rollo TEA experiments. I realize that this used pyrogallol but was this for pH adjustment or ??? Thanks for you patience and information! BTW, I've had some very nice results with the Rollo TEA and only went pursuing catechol concoctions to get the easier VC compatible negs with catechol's stain color.
    Craig Schroeder

  10. #10

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    Quote Originally Posted by craigclu
    I carelessly used the term "monobath", thinking of a single mix concentrate and not self-fixing. I was curious as to possible reducers (I guess that's the term to use) that could be incorporated into the single solution concentrate. Are the potassium family likely to be more soluble in TEA/PG as they are in water? I've got some things doing most of what I want them to with a blend of TEA and PG but require a pH boost with sodium carbonate or sodium hydroxide secondary additions and had a curiosity about what possibly could be used in a single solution concentrate. I like how my catechol, ascorbic acid, Dimezone-S (or phenidone, too) and BZT go into suspension at lower temps in the PG. I then top off with TEA and get blends that don't give viscosity/freezing battles in my cold basement darkroom.

    I'm feeling re-energized about photography in the last couple of years by getting more involved in tuning developers/curves to my tastes and needs. I feel like I'm 95% of the way to what I want at this point so I'm at the point where it gets harder! I might be wishing for too much to incorporate this all into a single solution developer.
    I'd try it with TEA as the only alkali first (I use TEA from The Chemistry Store).

    If you feel the need to boost the pH, stir a tablespoon of carbonate into the working developer.
    Tom Hoskinson
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